Hot-wire anemometry and cylinder wake

Project · Project 65

Experimental aerodynamic measurements using hot-wire anemometry, including full sensor characterization, calibration, and wake flow analysis of a circular cylinder.

Sensor characterisation and calibration

The probe's dynamic response was determined through impulse analysis, obtaining a cutoff frequency of 10 kHz, ensuring suitability for resolving turbulent fluctuations. The hot-wire was calibrated using King's Law over a velocity range of 3–20 m/s, achieving excellent fit accuracy (R² = 0.9998), enabling reliable conversion of voltage signals into instantaneous velocity.

E² = A + B · Uⁿ

King's Law calibration curve/assets/img/projects/hotwire-calibration.png

Fig. 1 — Final King's law calibration curve, E² = A + BUⁿ.

Wake analysis

The wake of a circular cylinder (D = 32 mm) was then analysed using high-frequency sampling, computing power spectral densities to identify vortex shedding frequencies and their dependence on freestream velocity.

Power spectral density at 4, 8 and 12 m/s/assets/img/projects/hotwire-psd.png

Fig. 2 — Power spectral density for 4, 8 and 12 m/s.

Turbulence statistics revealed significant velocity deficits and high turbulence intensity (27–32%) in the wake. Time-frequency analysis via STFT was additionally implemented to track the shedding frequency evolution, confirming temporal stability and agreement with Strouhal-based theoretical predictions.

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